How to remove columns after particular columns in datatable

for (int i = 0; i < ds.Tables.Count; i++)     
           {     
               for (int j = 0; j < ds.Tables[i].Columns.Count; j++)  
                  {                     
   if (ds.Tables[i].Rows[7][j].ToString().Trim().Contains("Lead Time (WEEKS)")) 
                       {         
                   int y = j;     
                       if (ds.Tables[i].Rows[7][y + 1].ToString().Trim() == "" || ds.Tables[i].Rows[7][y + 1].ToString().Trim() != "")   
                         {                                int y1 = y + 1;
 ds.Tables[i].Columns.RemoveAt(y1);    
                        }       
                 }              
      }              
  }